chore(deps): pin prom/prometheus docker tag to bc1794e (#7874)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

docker/docker-compose.prod.yml

@@ -78,7 +78,7 @@ services:
     container_name: immich_prometheus
     ports:
       - 9090:9090
-    image: prom/prometheus
+    image: prom/prometheus@sha256:bc1794e85c9e00293351b967efa267ce6af1c824ac875a9d0c7ac84700a8b53e
     volumes:
       - ./prometheus.yml:/etc/prometheus/prometheus.yml
       - prometheus-data:/prometheus